The invention relates to a method for supplying an electric domestic appliance, with a circuit device for supplying internal consumers from a low voltage supply network, especially from a network which is supplied by a photovoltaic power station or wind power station, with a circuit arrangement for energy management through which the internal consumers are classified according to their energy requirements and are supplied with energy, and with a control arrangement and measurement sensors for the control of item treatment programs. The invention also further relates to a domestic appliance suitable for carrying out said method.
The direct supply of electric appliances by means of an extra low voltage from a low voltage supply network, for example an extra low voltage network operated by regenerative energy sources such as photovoltaic or wind power stations and buffered by batteries, is widely known. For example tools with rechargeable batteries or domestic appliances such as shavers are generally known. Such appliances no longer require power supplies in the electric appliances, through which a feed voltage for electric circuits of the control device for an electric appliance is established via a transformer and a rectifier and current smoothing circuit from the feed taken from a normal alternating current domestic network, by means of a single-phase AC voltage of 230 V˜. The operation of high-power components, e.g. of heating devices and drive motors, continues to be possible for devices of which the control device is supplied through a rectifier and current smoothing circuit through the voltage (230 V˜) offered by the domestic network. A general DC/DC converter in a circuit device for supplying internal consumers of an electric domestic appliance for conversion to a low voltage supply network is also conceivable.
In a solar power plant in accordance with DE 35 02 826 A1 a consumer is switched off on the one hand by a control device after the operating voltage at the rechargeable battery drops below a predetermined level. Such switching off protects the rechargeable battery against deep discharge. On the other hand the consumer is also automatically switched back on after the return of a suitably high supply voltage, wherein the voltage for switching back on is significantly higher than the switch-off voltage. This ensures that the battery, after the protective switch-off, is initially recharged completely or at least to a significant extent before the consumer is connected again. To this end the control device can also adapt the switching off and switching on to markedly different loads from consumers. Thus weak consumers, by contrast with stronger consumers, are already switched on again when the battery has not yet been completely recharged, but despite the switching back on of a weak consumer the charging operation can continue to be maintained. This especially enables longer operating pauses to be avoided, especially with weak consumers. However such a system is ill suited to electrical consumers having a number of internal consumers at least operated partly in parallel with different consumption characteristics.
A generic method and an arrangement for switching off consumers in accordance with DE 196 37 574 A1 make provision for a voltage source with a number of connected consumers not to switch off all consumers immediately when the voltage falls below a threshold value. Instead the immediate switching off of all consumers is avoided by a regulation circuit determining which of the connected consumers should be subject to an individually-staggered switch-off or should only be supplied with energy at a reduced level. In such cases the sequence of reductions or switch offs is defined in accordance with the type of consumer (heating device, power device) and in accordance with their energy requirement. Such a staggered switch-off in some cases entirely avoids one or another consumer being switched off. There is no provision for a differentiated switching back on. This is also why such a known method is unsuitable for electric domestic appliances with a number of internal consumers.
Charging and discharging management is already known from DE 203 02 943 U1, for charging batteries from a number of different energy sources in the most protective manner possible, avoiding overcharging and undercharging and making the optimum use of the individual energy sources. In such cases, for the operation of electric consumers, the energy taken from them, e.g. for observing the discharge currents, is also monitored, wherein no further details are provided about the influence from the different measured discharge currents. Otherwise the management primarily relates to taking account of all possible known types of energy source for the charging process of one or more rechargeable batteries. A solution for the management of a number of internal consumers in an electric domestic appliance cannot be derived from this patent.